I use the WordPress SEO plugin in almost all my WP installments and I think it is a brilliant plugin. Thank you very musch Yoast for sharing it with us!
I do have a small simple critique or feedback. When editing a post or a page, the title of the panel where you write your meta title, meta description etc. the panel is titled "WordPress SEO by Yoast". This is not a very useful or userfriendly title for the panel. Most of my clients have no idea what this means and who Yoast is and will never know.
If I may come with a suggestion for a more userfriendly title for the panel.
"SEO - meta title and description" or something like this.
I do understand that you (Yoast) should get credit for this panel/plugin, but maybe credit could be placed in the right side or bottom of this panel.
Anyway, this is just a suggestion to make your plugin even more userfriendly to most people. :-)
Again, thank you for your great plugin.